We recommend that more evidence should be gathered from clinical studies and trials to clarify our diagnostic criteria and management strategies.

Background: Germline-speci®c differential DNA methylation that persists through fertilization and embryonic development is thought to be thè imprint' distinguishing the parental alleles of imprinted genes. If such methylation is to work as the imprinting mechanism, however, it has to be reprogrammed following each passage through the germline. Previous studies on maternally methylated genes have shown that their methylation imprints are ®rst erased in primordial germ cells (PGCs) and then re-established during oocyte growth.

A new imprinted gene has been discovered in mice using the technique of restriction landmark genomic scanning (RLGS) with methylation sensitive enzymes. Eight out of 3,100 strain-specific NotI and BssHII spots were identified as imprinted in reciprocal F1 hybrids. Subsequently, we isolated a genomic clone for one locus on proximal chromosome 11 near the Glns locus, an imprinted region in uniparental disomic mice, and its corresponding cDNA clone. Expression of this transcript from the paternal allele was established using RT-PCR of reciprocal F1-hybrid mice. The amino-acid sequence deduced from the cDNA showed significant homology to the U2 small nuclear ribonucleoprotein auxiliary factor 35 kDa subunit.

The purpose of this study was to determine the viability of Tongue Coating Index, which is a new method for evaluating tongue-coating status. To determine the reliability and reproducibility of our new evaluation criteria (Score 0: Tongue coating not visible; Score 1: Tongue coating thin, papillae of tongue visible; Score 2: Tongue coating very thick, papillae of tongue not visible), 10 observers evaluated 20 photographs of tongues. Each tongue surface was divided into nine sections. Observers evaluated each section according to our new criteria and each score for tongue-coating status was recorded in the pertinent section of the Tongue Coating Record form. They repeated the same evaluation 2 weeks after the first evaluation. The relationship between the scores obtained and number of oral microorganisms was investigated in 50 edentulous patients. Tongue coating was collected from the tongue surface after evaluation of tongue-coating status. The total number of anaerobic bacteria and the number of Candida species were counted from the specimens collected. Interobserver agreement and intraobserver agreement were 0.66 and 0.80 by Cohen's kappa, respectively. No significant difference was observed in the number of Candida species among the three scores. The number of total anaerobic bacteria, however, was significantly different among the scores (P < 0.05). Therefore, we conclude that our method for evaluating tongue-coating status offers new criteria that are superior in reliability and reproducibility, and that also reflect the total number of anaerobic bacteria present on the dorsum of the tongue.

Maintenance-type DNA methyltransferase (Dnmt1) is usually down-regulated in non-proliferating cells. In the present study, we detected significant expression of Dnmt1 protein in adult mouse brain where the majority of the cells are in a post-mitotic state. A significant amount of Dnmt1 protein was fractionated into the post-nuclear fraction for both cerebrum and cerebellum. The Dnmt1 in this fraction was enzymatically active. An immunofluorescence study revealed that Dnmt1 protein was mainly expressed in neurons and seemed to be localized in the cytoplasmic compartment. Primary culturing of neurons confirmed the expression and localization of Dnmt1 in the cytoplasmic compartment. The findings that the Dnmt1 transcript in the brain utilized the somatic-type exon and that the apparent size of the Dnmt1 protein in the cytoplasm was identical to that in proliferating culture cells indicate that the cytoplasmic Dnmt1 in neurons was of the somatic-type.